Mammalian aspartate transcarbamylase (ATCase): Sequence of the ATCase domain and interdomain linker in the CAD multifunctional polypeptide and properties of the isolated domain

Abstract

ABSTRACTphosphate and L-aspartate in the de novo pyrimidine biosynthetic pathway. Escherichia coli ATCase, an allosteric enzyme (1, 2), is a 303-kDa molecule that can be dissociated into two catalytic trimers and three regulatory dimers (3-6). Lipscomb and his associates (7-9) have determined the three-dimensional structure of E. coli ATCase in both R ("relaxed") and T ("taut") allosteric conformations. Bacillus subtilis ATCase, a trimer of 34-kDa catalytic chains that lacks regulatory chains, resembles the isolated E. coli ATCase catalytic trimer (10). Lerner and Switzer (11)